The proposed research will explore the development of a laboratory animal model for the experimental analysis of both chronic, long-term drug use and HIV/AIDS. The nonhuman primate model to be explored will combine current oral drug dosing techniques with a well-defined simian immunodeficiency virus (SIV-macaque model of HIV/AIDS to investigate the viral, behavioral, and CNS consequences associated with chronic exposure to drugs of abuse, SIV viruses, and their combination. First, oral self-dosing techniques will be used to establish chronic morphine dependence in macaque monkeys, with morphine dependence being assessed and monitored via the recording of continuous telemetric data on body temperature and general activity, and via behavioral observations of drug dependence. Second, the effects of chronic morphine self-dosing on immune function will be concurrently evaluated by assessing immune function during the development of dependence, during chronic morphine dependence, and during periods of withdrawal (short-term abstinence and precipitate withdrawal). Third, the effects of morphine dependence on the disease process will be assessed by comparing all measures (body temperature, general activity, immune system function) in groups of morphine-dependent and drug-free animals throughout the course of SIV disease progression. The development of a nonhuman primate model for the investigation of the effects of both chronic drug administration and SIV disease will be an important tool in advancing the scientific understanding of the relationship between drug use and HIV/AIDS, and their consequences on cognitive/behavioral processes.